Aviation Safety Letter 2/2003
The Hazard of Aircraft Refuelling with Plastic "Jerrycans"
Spring is almost with us, and so too is the hazard of aircraft refuelling. When you refuel your aircraft from a plastic container that is not grounded to the aircraft, it creates a definite fire hazard. Unfortunately, many aircraft have been lost during this seemingly simple process. Aircraft and lawnmower fuel tanks do not share the same environmental factors that create this hazardous situation. Nevertheless, the same risk is present when you refuel a lawnmower. The difference is based on the electrostatic potential of the two machines. Given the proper temperature, humidity, barometric pressure, and wind conditions, the aircraft becomes electrically charged because its wing and structure area are exposed to air, which charges them electro-statically. Likewise, the plastic fuel container gets charged when being refuelled. If you do not ground the container to the aircraft structure, or directly to the aircraft fuel tank, with the help of a wire - preferably touching the bottom of the plastic container - and a clamp on the fuel tank before you start dispensing fuel, the difference in electrostatic potential makes the charged electrons race from the aircraft tank to the fuel container at an accelerated rate in order to establish a balance of electron potential between the two structures. This occurs in microseconds and brings about a source of ignition of the fuel molecules in movement at the surface of the gasoline and the ensuing potential for fire. So be careful, and make sure to ground the aircraft to the ground and ground the fuel container to the aircraft before refuelling. Using a metal fuel container, a metal funnel, bonding wire and a clamp to ground all articles to the aircraft should ensure safe fuel transfer. Equally important is to have at-hand, a fire extinguisher of sufficient size to save your aircraft handy when refuelling. The value of your life and of your aircraft is worth countless numbers of fire extinguishers. Happy flying!
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